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/*!
* \file
* \brief test program for MIMO demapper
* \author Bogdan Cristea
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2012 (see AUTHORS file for a list of contributors)
*
* This file is part of IT++ - a C++ library of mathematical, signal
* processing, speech processing, and communications classes and functions.
*
* IT++ is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* IT++ is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along
* with IT++. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include "itpp/itcomm.h"
#include <string>
using namespace std;
using namespace itpp;
int main()
{
//parameters
int const_size = 16;
string demapper_method[] = {"Hassibi_maxlogMAP", "GA", "sGA", "mmsePIC", "zfPIC"};
string code_name = "V-BLAST_MxN";
int em_antennas = 2;
int rec_antennas = 2;
int channel_uses = 1;
int perm_len = pow2i(6);//permutation length
//QAM modulator class
QAM mod(const_size);
//Space-Time code parameters
STC st_block_code(code_name, const_size, em_antennas, channel_uses);//generate matrices for LD code (following Hassibi's approach)
//SISO blocks
SISO siso;
siso.set_constellation(mod.bits_per_symbol(), mod.get_symbols(),
mod.get_bits2symbols());
siso.set_st_block_code(st_block_code.get_nb_symbols_per_block(),
st_block_code.get_1st_gen_matrix(), st_block_code.get_2nd_gen_matrix(),
rec_antennas);
siso.set_noise(1e-1);
//bits generation
bvec bits = randb(perm_len);
//QAM modulation
cvec em = mod.modulate_bits(bits)/sqrt(double(em_antennas));//normalize emitted symbols
//ST code
cmat S = st_block_code.encode(em);
//internal variables
int symb_block = st_block_code.get_nb_symbols_per_block();
int nb_symb = perm_len/mod.bits_per_symbol();//number of symbols at the modulator output
int nb_subblocks = nb_symb/symb_block;//number of blocks of ST code emitted in an interleaver period
int tx_duration = channel_uses*nb_subblocks;//transmission duration expressed in number of symbol periods
//ideal channel
if (em_antennas != rec_antennas)
{
return EXIT_FAILURE;
}
cmat mimo_channel = eye_c(em_antennas);
cmat rec(tx_duration,rec_antennas);
for (int ns=0;ns<nb_subblocks;ns++)
{
rec.set_submatrix(ns*channel_uses, 0,
S(ns*channel_uses, (ns+1)*channel_uses-1, 0, em_antennas-1)*
mimo_channel);
}
//first decoder
vec demapper_apriori_data(perm_len);
vec demapper_extrinsic_data(perm_len);
demapper_apriori_data.zeros();//a priori information of emitted bits
cmat ch_att(em_antennas*rec_antennas, tx_duration);
ch_att = kron(reshape(mimo_channel, em_antennas*rec_antennas, 1), ones_c(1, tx_duration));
siso.set_impulse_response(ch_att);
BERC ber;
for (unsigned int n = 0; n < sizeof(demapper_method)/sizeof(demapper_method[0]); ++n)
{
siso.set_demapper_method(demapper_method[n]);
siso.demapper(demapper_extrinsic_data, rec, demapper_apriori_data);
//show results
ber.count((demapper_extrinsic_data > 0), bits);
cout << demapper_method[n] << ", BER = " << ber.get_errorrate() << endl;
demapper_extrinsic_data.zeros();
}
}
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